2c7o

HhaI DNA methyltransferase complex with 13mer oligonucleotide containing 2-aminopurine adjacent to the target base (PCGC:GMGC) and SAH

spinqualitylabelsall models 2c7o, resolution 1.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2c7o is a 3 chain structure with sequence from Haemophilus haemolyticus and Synthetic construct. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.9Å Ligands: 2PR, 5CM, SAH, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function MTH1_HAEPH This methylase recognizes the double-stranded sequence GCGC, causes specific methylation on C-2 on both strands, and protects the DNA from cleavage by the HhaI endonuclease. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed DNA base flipping is an important mechanism in molecular enzymology, but its study is limited by the lack of an accessible and reliable diagnostic technique. A series of crystalline complexes of a DNA methyltransferase, M.HhaI, and its cognate DNA, in which a fluorescent nucleobase analogue, 2-aminopurine (AP), occupies defined positions with respect the target flipped base, have been prepared and their structures determined at higher than 2 A resolution. From time-resolved fluorescence measurements of these single crystals, we have established that the fluorescence decay function of AP shows a pronounced, characteristic response to base flipping: the loss of the very short (approximately 100 ps) decay component and the large increase in the amplitude of the long (approximately 10 ns) component. When AP is positioned at sites other than the target site, this response is not seen. Most significantly, we have shown that the same clear response is apparent when M.HhaI complexes with DNA in solution, giving an unambiguous signal of base flipping. Analysis of the AP fluorescence decay function reveals conformational heterogeneity in the DNA-enzyme complexes that cannot be discerned from the present X-ray structures. Time-resolved fluorescence of 2-aminopurine as a probe of base flipping in M.HhaI-DNA complexes.,Neely RK, Daujotyte D, Grazulis S, Magennis SW, Dryden DT, Klimasauskas S, Jones AC Nucleic Acids Res. 2005 Dec 9;33(22):6953-60. Print 2005. PMID:16340006 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also DNA methyltransferase 3D structures

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